How to fix Error 103 on Windows 11

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Why This Error Happens

Error 103 (ERROR_SEM_IS_SET) occurs when a process attempts to set a semaphore object that is already in a “set” state, meaning another process or thread is still holding a lock on that shared resource. This typically happens when a service, driver, or application does not release its synchronization handle properly due to a crash, an unexpected termination, or corrupted driver code. It’s frequently seen with print spoolers, legacy hardware drivers, or third-party software that manages shared resources through kernel-level synchronization objects.

Step-by-Step Resolution Guide

  1. Restart the affected service
  • Press Win + R, type services.msc, and press Enter.
  • Locate the service tied to the error (commonly Print Spooler or a specific hardware/driver service).
  • Right-click it and select Restart. This releases any stuck semaphore handles.
  1. Check Event Viewer for the source process
  • Open Event Viewer (Win + X → Event Viewer).
  • Navigate to Windows Logs > System and Windows Logs > Application.
  • Filter by Event ID 103 to identify which driver or application triggered the semaphore conflict.
  1. Update or reinstall the responsible driver
  • Open Device Manager (Win + X → Device Manager).
  • Find the device linked to the failing process (identified in Step 2).
  • Right-click → Uninstall device, then restart your PC to let Windows reinstall a clean driver.
  • Alternatively, download the latest driver from the manufacturer’s website.
  1. Clear stuck spooler/resource files (if print-related)
  • Stop the Print Spooler service via services.msc.
  • Navigate to C:\Windows\System32\spool\PRINTERS and delete all files inside.
  • Restart the Print Spooler service.
  1. Run System File Checker to repair corrupted system components
  • Open Command Prompt as Administrator.
  • Run: sfc /scannow
  • Follow with DISM /Online /Cleanup-Image /RestoreHealth if corruption is found.

Alternative or Verification Steps

  • Verify the fix: Reopen the application or reconnect the device that previously triggered Error 103, and confirm no error dialog appears. Check Event Viewer to ensure Event ID 103 is no longer being logged.
  • Alternative solution: If the issue persists, perform a clean boot (msconfig → Selective startup, disable all non-Microsoft services) to isolate a conflicting background application that may be locking the semaphore.